JP2000306490A - Earth leakage breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a zero-phase sequence current transformer from being infiltrated by arc gas when a current is interrupted. SOLUTION: This earth leakage breaker is structured by dividing its insulating container into three upper and lower parts of a case 1, an intermediate case 25 and a cover 2. Fixed contacts 21, 23 and a movable contact 22 to bridge them are stored in the case 1, an overcurrent trip device 8, a zero-phase sequence current transformer 11 and a switch mechanism 13 are stored in the intermediate case 25, and a holder 12 slidably penetrating through an angular hole 28 on the bottom wall 25a of the intermediate case 25 to apply switch operation to the movable contact 22 by being driven by the switch lever 30 of the switch mechanism 13 is straightly moved perpendicularly to the bottom wall 25a. Only a slight gap between the holder 12 and the bottom wall 25a in the angular hole 28 is required for the holder 12 to straightly move, and arc gas produced in the case 1 does not reach the zero-phase sequence current transformer 11 in the intermediate case 25 by being interrupted by the bottom wall 25a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage circuit breaker used for protecting a low-voltage path from a ground fault or the like, and more particularly to an arrangement of a zero-phase current transformer.

[0002]

2. Description of the Related Art FIG. 3 is a longitudinal sectional view showing an ON state of a conventional three-electrode leakage breaker. In FIG. 3, a power supply side terminal 3 and a load side terminal 4 of each pole are provided at the front and rear (left and right in FIG. 3) both ends of a box-shaped insulating container composed of a case 1 having an open upper surface and a cover 2 having an open lower surface. A fixed contact 5 integrated with the power supply terminal 3, a movable contact 6 having one end in contact with the fixed contact 5, and a lead wire 7 connected to the other end of the movable contact 6 are provided. The heater conductor 9 of the overcurrent trip device 8 connected to the lead wire 7 is formed by a relay conductor 10 joined to the heater conductor 9 by brazing or welding and integrally formed with the load-side terminal 4. A zero-phase current transformer 11 having the relay conductor 10 as a primary conductor is disposed between the overcurrent trip device 8 and the load terminal 4. Note that a fixed contact and a movable contact are attached to each contact end of the fixed contact 5 and the movable contact 6, respectively.

FIG. 4 is a perspective view showing a shape of a primary conductor 10 penetrating a zero-phase current transformer 11. 4, each phase (R, S, T phase) primary conductor 10 _R to 10 _T of configured shape shown by punching and bending from a plate conductor, and is formed symmetrically R phase conductor 10 _R the intermediate portion and the T-phase conductor 10 _T passing through the zero-phase current transformer 11 is biased toward the S-phase conductor 10 _S, have different S-phase conductor 10 _S shape.

The movable contact 6 is cantilevered at a right end in FIG. 3 by a holder 12 made of an insulating material, and the holder 12 is rotatably supported by the case 1 via an opening / closing shaft (not shown). An opening / closing mechanism 13 is connected to the center pole holder 12,
By the opening and closing operation of the opening and closing handle 14 protruding from the cover 2, the movable contact 6 is driven to open and close in the direction indicated by the arrow through the holder 12. On the other hand, when an overload current occurs, the bimetal 15 heated by the Joule heat generated by the heater conductor 9 of the overcurrent tripping device 8 bends, so that a large current such as a short-circuit current flows. Is instantaneously sucked, the trip crossbar 17 is driven, the latch of the opening / closing mechanism 13 is released, and the movable contact 6 is opened. Further, when an imbalance occurs between the currents of the respective poles flowing through the primary conductor 10 due to a ground fault, a secondary output is generated in the zero-phase current transformer 11, and the trip crossbar 17 is driven via an earth leakage trip device (not shown). Then, the movable contact 6 is opened.

When the movable contact 6 is opened, an arc is generated between the fixed and movable contacts. Therefore, in order to extinguish the arc, an arc extinguishing chamber 18 is provided so as to surround the movable contact 6. The arc extinguishing chamber 18 is constituted by a plurality of magnetic plates (grids) 19 having a V-shaped notch supported by an insulating support plate, and the arc is extinguished by drawing the arc into the grid 19 and dividing and cooling the arc.

[0006]

In the above-mentioned earth leakage breaker, a metal part which is exposed to an arc when a large current is interrupted,
For example, the movable / fixed contact, the movable contact 6, the grid 19, etc. are melted and scattered around due to the gas pressure generated by the arc heat. In this case, conventionally, there is a possibility that the metal melt may enter the inside of the zero-phase current transformer 11 and impair the interphase insulation of the primary conductor 10.

Further, conventionally, the overcurrent trip device 8 and the zero-phase current transformer 11 are installed so as to be close to each other between the load-side terminal 4 and the switching mechanism 13, and the zero-phase current transformer 11 is connected. The penetrating primary conductor 10 is joined to the heater conductor 9 of the overcurrent trip device 8, but the primary conductor 10 is, as shown in FIG.
Since the shapes of the central phase (S phase) and the left and right phases (R, S phases) are different, the heating characteristics of the bimetal 15 and the suction characteristics of the movable iron piece 16 in the overcurrent trip device 8 are affected by the primary conductor 10. Different between phases, the adjustment required a lot of man-hours. Also, an overcurrent trip device 8 as an overcurrent detection unit
And the zero-phase current transformer 11 as a leakage detecting unit are integrally formed, so that the structure is complicated and the assembling work has to be complicated.

It is an object of the present invention to protect a zero-phase current transformer from arc heat at the time of current interruption, and to reduce the man-hours for adjusting and assembling an overcurrent tripping device.

[0009]

According to the present invention, there is provided an insulating container comprising an upper case, an intermediate case made of a frame with a bottom wall, an upper case and a cover having an open lower surface. The holder for holding the movable / fixed contact and the arc-extinguishing chamber is housed in the case, and the movable / fixed contact is accommodated in the case. The phase current transformer and the overcurrent tripping device are housed in the intermediate case together with the opening / closing mechanism, and the holder is slidably penetrated through a bottom wall of the intermediate case (claim 1). ). According to the first aspect, the zero-phase current transformer is housed in the intermediate case which is separated from the case in which the movable / fixed contact that generates the arc is housed, and thus is isolated from the metal melt scattered by the arc heat. In addition, there is no possibility that the interphase insulation of the primary conductor is damaged.

[0010] Further, according to the present invention, the zero-phase current transformer is arranged on a side opposite to the overcurrent tripping device with the switching mechanism interposed therebetween (claim 2). According to this claim 2,
The overcurrent trip device and the zero-phase current transformer are separated into a power supply side and a load side with a switching mechanism in between, and the overcurrent trip device is affected by the primary conductor penetrating the zero-phase current transformer. At the same time, the overcurrent detection unit and the leakage detection unit are configured as separate units, thereby simplifying the structure.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
An embodiment of the present invention will be described. Here, FIG. 1 is a longitudinal sectional view of the earth leakage breaker in an ON state, and FIG. 2 is a plan view of FIG. Note that the same reference numerals are used for the portions corresponding to the conventional example. 1 and 2, power supply terminals 3 and 4 of respective poles are respectively disposed at both front and rear (left and right in FIG. 1) ends of a box-shaped insulating container, and an electric path therebetween is a zero-phase current transformer 11. And a rising portion 3a integral with the power supply terminal 3
Primary contact 20 joined to the primary conductor 20, one fixed contact 21 connected to the primary conductor 20 with a screw, a bridge-shaped movable contact 22 having one end in contact with the fixed contact 21, and the other end of the movable contact 22 The other fixed contact 23 and the fixed contact 2 that come into contact with each other
3 is formed by a relay conductor 24 joined to the heater conductor 9 of the overcurrent tripping device 8 connected to the load terminal 4 with a screw.

The relay conductor 24 has the same shape in each phase, unlike the conventional example (FIG. 4), and has substantially the same shape as that of the central phase (S phase) in FIG. Fixed contact 21,
A fixed contact and a movable contact are attached to each contact end of the movable contact 23 and the movable contact 22, respectively. The shape of the primary conductor 20 of each phase is substantially the same as the conventional primary conductor 10 shown in FIG.

Here, the insulating container of the circuit breaker is composed of a case 1 having an open upper surface, an intermediate case 25 composed of a frame having a bottom wall 25a, and a cover 2 having an open lower surface. Stacked as shown in FIG.
They are integrally tightened by screws 26 (FIG. 2) at the locations. The interiors of the case 1, the intermediate case 25 and the cover 2 are each partitioned into three poles by three rows of left and right phase spacing walls. Then, a pair of fixed contacts 21 and 23 before and after each pole, and a movable contact 22 bridging between them.
A pair of arc extinguishing chambers 18 respectively surrounding the front and rear ends of the movable contact 22 are housed in the case 1, and the opening / closing mechanism 13 and the overcurrent trip device 8 are housed in the intermediate case 25. The movable contact 22 is bent and formed in a symmetrical convex shape as shown in the figure, and is fixed by a contact spring 27 composed of a compression coil spring inserted between the movable contact 22 and the bottom wall of the case 1.
The holders 12 and 13 are pressed against each other, and their heads are fitted with prismatic holders 12 made of an insulating material via recesses at the lower ends thereof. The holder 12 is guided by a guide groove (not shown) formed in the case 1 so as to linearly move in the vertical direction in FIG.

On the other hand, on the bottom wall 25a of the intermediate case 25,
A rectangular hole 28 is formed along the contour of the holder 12 so as to correspond to the holder 12, and the holder 12 slidably penetrates the rectangular hole 28, and its upper end protrudes into the intermediate case 25. The fixed contacts 21 and 23 are both fastened to the lower surface of the intermediate case bottom wall 25a with screws (not shown). However, the intermediate case 25 is stacked on the case 1 as shown in FIG. To position. The primary conductors 2 connected to the fixed contacts 21 and 23 by screws, respectively.
The heater conductor 9 and the heater conductor 9 enter the intermediate case 25 through the opening of the bottom wall 25a.

The opening and closing mechanism 13 will not be described in detail,
An opening / closing lever 30 is provided, which rotates about the operating shaft 29 in accordance with the opening / closing operation of the opening / closing handle 14 in the left-right direction in FIG. The opening / closing lever 30 is formed in a trifurcated shape having three arms, and the tip of each arm is close to the upper end surface of the holder 12 in the ON state of FIG. In FIG. 1, when the opening / closing handle 14 is turned OFF to the left,
The opening / closing lever 30 is rotated clockwise, and the holder 12 is opposed to the contact spring 27, and the bottom wall 25a of the intermediate case 25 is
Vertically and straight down. Thereby, the movable contact 6 is opened, and the earth leakage breaker is turned off.

When the open / close handle 14 is turned ON in the right direction in FIG. 1 from the OFF state, the open / close lever 30 returns to the position shown in the drawing, and the movable contact 22 is pushed up by the contact spring 27 to close the pole. At this time, the holder 12 rises vertically and linearly to the intermediate case bottom wall 25a. When an overcurrent occurs, the latch of the opening / closing mechanism 13 is released by the operation of the overcurrent tripping device 8 via the trip crossbar 17, and the opening / closing lever 30 is driven to rotate clockwise to move the movable contact 6.
Opens. In addition, when a ground fault occurs, a secondary output is generated in the zero-phase current transformer 11, and the trip crossbar 17 is driven via an earth leakage trip device (not shown), and the movable contact 6 is opened. Here, since the holder 12 moves vertically and linearly with respect to the bottom wall 25a of the intermediate case 25,
Bottom wall 2 of holder 12 and intermediate case 25 in square hole 28
The gap with respect to 5a is kept to a very small minimum necessary for sliding the holder 12.

In FIG. 1, when the movable contact 22 is opened, an arc is generated between the movable and fixed contacts, and this arc is drawn into the arc-extinguishing chamber 18 to extinguish the arc. The arc gas containing the substance is discharged from an exhaust port (not shown) formed before and after the case 1. In that case, the arc gas generated in the case 1 is
Since the gap around the holder 12 at a is very small, it hardly penetrates into the intermediate case 25, so that the interphase insulation of the primary conductor 20 is not impaired by the adhesion of the molten metal.

In FIG. 1, the zero-phase current transformer 11 is installed on the power supply side opposite to the overcurrent trip device 8 with the switching mechanism 13 interposed therebetween, and the primary conductor 20 of the zero-phase current transformer 11 is It is not joined to the heater conductor 9 of the current trip device 8, and a relay conductor 24 having the same shape for each phase is joined to the heater conductor 9. Therefore, there is no difference in characteristics between the phases of the overcurrent trip device 8 due to the difference in the shape of the relay conductor 10 as in the related art.

Further, the overcurrent trip device 8 is connected to the load terminal 4.
Is connected to the relay conductor 24 to form one unit, and the zero-phase current transformer 11 forms another unit together with the power supply side terminal 3 and the primary conductor 20. Therefore, the overcurrent detection section and the leakage detection section are assembled as independent units, and are incorporated in the intermediate case 25, thereby simplifying the assembly operation.

[0020]

As described above, according to the present invention, the zero-phase current transformer housed in the intermediate case can be reliably protected from the arc gas generated in the case. Further, the characteristics of the overcurrent trip device do not vary between phases due to the influence of the primary conductor of the zero-phase current transformer, and the adjustment is simplified. Further, since the overcurrent detection unit and the leakage detection unit are configured as separate units, the assembling work and the assembling work into the insulating container are simplified.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an earth leakage breaker showing an embodiment of the present invention.

FIG. 2 is a plan view of the earth leakage breaker of FIG. 1;

FIG. 3 is a longitudinal sectional view of a leakage breaker showing a conventional example.

FIG. 4 is a perspective view of a zero-phase current transformer in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 2 Cover 3 Power supply side terminal 4 Load side terminal 8 Overcurrent trip device 11 Zero-phase current transformer 12 Holder 13 Opening / closing mechanism 14 Opening / closing handle 17 Trip crossbar 18 Arc extinguishing chamber 20 Primary conductor 21 Fixed contact 22 Fixed contact Element 23 Fixed contact element 25 Intermediate case 25a Bottom wall 27 Contact spring 28 Square hole 29 Operation axis 30 Opening / closing lever

Claims (2)

[Claims] 1. A power supply conductor and a load side terminal are respectively disposed at both front and rear ends of a box-shaped insulating container, a current-carrying conductor forming an electric path connecting these terminals, and a zero-phase transformer having the current-carrying conductor as a primary conductor. Flower, a movable contact and a fixed contact for opening and closing the electric circuit, an arc-extinguishing chamber surrounding the movable contact, an opening and closing mechanism for opening and closing the movable contact via an insulator holder, and a trip operation for the opening and closing mechanism. An earth leakage breaker configured such that an overcurrent trip device to be operated is housed in the insulating container, wherein the insulating container has a case with an open upper surface, an intermediate case made of a frame with a bottom wall, and a cover with an open lower surface. And the movable contact is configured so that the holder is linearly moved perpendicularly to the bottom wall of the intermediate case and is driven to open and close. Arc chamber Housed in the case, the zero-phase current transformer and the overcurrent trip device are housed in the intermediate case together with the opening / closing mechanism, and the holder is slidably penetrated through a bottom wall of the intermediate case. An earth leakage breaker characterized by the following. 2. The earth leakage breaker according to claim 1, wherein said zero-phase current transformer is arranged on a side opposite to said overcurrent tripping device with said switching mechanism interposed therebetween.